Bring 2 quarts of water to a boil.
While the water boils, get your ingredients ready. Shave or grate the parmesan and chop the basil for serving.
Add the penne and salt to the boiling water and cook according to the package directions. Mine took 9 minutes.
When the pasta is done, drain and reserve 1/4 cup of the pasta water.
Return drained pasta to the hot pan and immediately add the sun dried tomato pesto and mozzarella cheese. Stir to combine.
TASTE! If it's a little dry, add the reserved pasta water 1 tbsp at a time.
Serve immediately with fresh shaved parmesan and chopped basil. Enjoy!